Modern digital cameras, such as complementary metal-oxide-semiconductor (CMOS) cameras, frequently employ a method of image acquisition in which each frame is recorded by scanning across the frame row by row from top to bottom (or column by column across the frame) rather than by taking a single snapshot of the entire scene at a single point in time. Thus, not all parts of the image may be recorded at the same time. This method of image acquisition is sometimes called rolling shutter, because the shutter is moving (e.g., rolling) across the image area of the scene.
Due to the rolling shutter, visual distortions may be introduced and may be visually apparent when the entire image is displayed. In general, any movement of the camera as the image is captured may result in a warping or distortion of the image. Images captured using rolling shutter acquisition may exhibit different types of visual effects or distortions. One type of distortion may be caused by the camera not being held completely still throughout the entire process of scanning a frame. If the camera is moving horizontally, the image gets sheared. If the camera moves vertically, image is stretched or compressed.
For example, in images captured while a camera is vibrating, such when used from a moving vehicle, a wobble distortion may be created. Video exhibiting this distortion may appear to wobble unnaturally in a jelly-like fashion. Similarly, if a camera moves from side to side, a skew distortion may result in which the image may bend diagonally in one direction or another. If a CMOS camera sensor is used to take an image of a moving object, different areas of the object may appear smeared or to change proportion as compared to other areas of the object.